Pipecolic acid elevation in plasma and cerebrospinal fluid of two patientswith pyridoxine-dependent epilepsy

Diagnosis of pyridoxine-dependent epilepsy is based an the clinical respons e to high-dosage application of pyridoxine. Here, we report on 2 patients w ith pyridoxine-dependent epilepsy with significant elevation of pipecolic a cid concentrations in plasma and cerebrospinal fluid (CSF) and further incr ease of pipecolic acid in CSF during a 72-hour pyridoxine withdrawal in 1 o f them. Patients with non-pyridoxine-dependent epilepsy had normal pipecoli c acid concentrations in plasma and significantly lower concentrations in C SF. High plasma and CSF pipecolic acid concentrations might provide a diagn ostic marker in pyridoxine-dependent epilepsy.